CALIFORNIA WATER BIRDS. 7 



the Greater and Sooty. Shearwaters do not rear their 

 young during the sojourn on the North Atlantic* 



The Black-vented Shearwaters at Monterey were un- 

 doubtedly migrating to a breeding habitat further south. 

 While their destination may have been north of the equa- 

 tor, it seems highly probable that they did not stop short 

 of the Southern Hemisphere. There was ample time for 

 migration to the South Temperate Zone, for they were 

 speeding southward at a rate apparently equal to that of 

 the fastest express train. Continuing their flight half of 

 each day, a few days would suffice to cover several thou- 

 sand miles. If reproduction was postponed until Feb- 

 ruary, the height of the season in Wilson's Petrel on 

 Kerguelen Island (Eaton, Philos. Trans. Roy. Soc. Lon- 

 don, vol. 168, p. 134), over two weeks might elapse before 

 it would be necessary for the Monterey migrants to be on 

 their breeding grounds. f 



A collation of the facts bearing upon migration scattered 

 through the two volumes of Sclater and Hudson's 'Argen- 

 tine Ornithology ' reveals that migratory movements occur 

 in South America similar to those in North America, 

 southern winter with its failure of food forcing- the birds 

 to move toward the equator. The transmigration from 

 the northern continent, however, has no corresponding 

 parallel in the southern. J The smallness of the area to 

 be depopulated south of the Tropic of Capricorn seem- 

 ingly explains the absence of such migration, there being 

 no need for retreat to antipodean temperate latitudes to 



* The Pink-footed Shearwater and several other members of the order 

 Tubinares should be included with the species occurring but not breeding, 

 so far as discovered, on northern waters. 



t A greater length of time might transpire, for the nesting season is 

 protracted through the southern summer into March in the Dark-bodied 

 Shearwater (Buller, I.e., p. 232). 



t Nevertheless, it may be that there is some migration of indigenous 

 birds from temperate and tropical South America extending to tropical 

 North America. 



